Dopaminergic nervous system

Watanabe H, Ohta H, Imamura L, Asakura W, Matoba Y, Matsumoto K. (1991). Effect of Panax ginseng on age-related changes in the spontaneous motor activity and dopaminergic nervous system in the rat. Jpn J Pharmacol. 55(1) 51-56. 

The rate of pregnancy-blocking is also reduced when the strange male belongs to an inbreeding strain or on administration of alpha-methyl dopa suggesting that dopaminergic nervous system are involved in the Bruce effect (338). 

DAT is predominantly expressed by dopaminergic brain neurons, NET by noradrenergic neurons in the central and peripheral nervous system, and SERT is restricted to the axons of serotonergic neurons, which originate in the raphe nuclei and innervate numerous higher brain regions therefore SERT is widely distributed in the brain. Outside the brain, 5HT transport can be measured on non-neuronal cells (e.g. platelets, lympho-blastoid cells and smooth muscle cells) most of the 5HT appearing in the circulation is taken up by platelets. 

The nigrostriatal tract is one of the four main dopaminergic pathways in the central nervous system. About 75% of the dopamine in the brain occurs in the nigrostriatal pathway with its cell bodies in the substantia nigra, whose axons project in the corpus striatum. Degeneration of the dopaminergic neurons in the nigrostriatal system results in Parkinsons disease. 

Nemeroff C. The interaetion of neurotensin with dopaminergic pathways in the central nervous system Basie neurobiology and implications for the pathogenesis and treatment of schiiphrenia. Psychoneuroendocrinology ll(l) 15-37, 1986. 

Dopamine is a catecholamine neurotransmitter in the CNS and at some ganglia in the autonomic nervous system. To date, three main types of receptors have been found D1( D2, and D3. The main dopaminergic systems in the brain are the nigro-neostriatal... 

Dean, B., Bradbury, R., and Copolov, D.L., Cannabis-sensitive dopaminergic markers in postmortem central nervous system changes in schizophrenia, Biol. Psychiatry, 53, 585, 2003. 

L-dopa is effective in the treatment of Parkinson s disease, a disorder characterised by low levels of dopamine, since L-dopa is metabolised into dopamine. However, this biosynthesis normally occurs in both the peripheral nervous system (PNS) and the central nervous system CNS. The related drug carbidopa inhibits aromatic L-amino acid decarboxylase only in the periphery, since it does not cross the blood-brain barrier. So, when carbidopa is given with L-dopa, it reduces the biosynthesis of L-dopa to dopamine in the periphery and, thus, increases the bioavailability of L-dopa for the dopaminergic neurons in the brain. Hence, carbidopa increases the clinical efficacy of L-dopa for Parkinsonian patients. 

Schizophrenia is a chronic, complex psychiatric disorder affecting approximately 1% of the population worldwide. The chronic nature of the illness, in addition to the early age of onset, results in direct and indirect health care expenditures in the U.S., which amount to approximately 30 to 64 billion dollars per year [4]. It is perhaps the most devastating of psychiatric disorders, with approximately 10% of patients committing suicide. The dopamine hypothesis of schizophrenia postulates that overactivity at dopaminergic synapses in the central nervous system (CNS), particularly the mesolimbic system, causes the psychotic symptoms (hallucinations and delusions) of schizophrenia. Roth and Meltzer [5] have provided a review of the literature and have concluded a role for serotonin as well in the pathophysiology and treatment of schizophrenia. The basic premise of their work stems from the known interaction between the serotonergic and dopaminergic systems. 

Although the precise mechanism for the hypothermia induced by chlordecone is unknown, data suggest a role of central nervous system (CNS) dopaminergic or a-noradrenergic activity in... 

Fig. 3.8 Protection of central nervous system (CNS) dopaminergic neurons from 6-OHDA-induced apoptosis by 8. Untreated top), 6-OHDA plus vehicle treatment middle) and 6-OHDA plus 250 pM 8 down) were stained with anti-tyrosine hydrolase antibody. The number of TH-immunoreactive cells clustered in dienecephalons was examined (arrows). After 250 pM 8 treatment, three of five animals showed a normal number of TH-immunoreactive cells with normal morphology (Reprinted from Beuerle, 2007. With friendly permission of Taylor Francis, http //www.informaworld.com)...

Dopamine is a major catecholamine neurotransmitter in the central nervous system (37) that is involved in the neuroregulation of locomotor activity, emotion, and neuroendocrine secretion (38,39). Clinically, dopaminergic drugs are used to treat Parkinson s disease and schizophrenia by activating or blocking dopamine receptors, respectively (40). 

To date, several studies have indicated that environmental stresses, such as ROS, may influence proteasome function in the central nervous system. If proteasome dysfunction specifically occurs in dopaminergic neurons, then the possibility that stress-dependent vulnerability of proteasomes ceases mandatory destruction of ubiquitinated proteins and influences the onset of PD can not be ruled out completely. However, these observations appear to be superficial so far and this point of view is only just beginning to emerge. Therefore, we think such paradigms are beyond the scope of this review and await future comprehensive analysis. 

Dextroamphetamine is a powerful stimulant of the nervous system that manifests its effects by releasing dopamine and norepinephrine from presynaptic nerve endings, thus stimulating central dopaminergic and noradrenergic receptors. In certain doses it strengthens the excitatory process in the CNS, reduces fatigue, elevates mood and the capacity to work, reduces the need for sleep, and decreases appetite. 

The effects on sleep result from the psychostimulant and sympathomimetic actions of these drugs. They enhance noradrenergic, dopaminergic and serotonergic transmission in the central and peripheral nervous system mainly by increasing transmitter release and also inhibitory uptake. 

Neuroleptic drugs are used in the treatment of psychosis, such as schizophrenia they are generally antagonist ligands of dopamine at the central nervous system level. " Indications and therapeutic effects of the various families of neuroleptics result from two factors. The first one is the specifity of the ligand toward the different types of dopaminergic receptors, which are unequally distributed in the... 

None of the TCAs seem to have an effect on dopaminergic neurotransmission in the central nervous system (CNS). This has been supported by the lack of alterations in dopamine receptor sensitivity in chronically treated patients who have shown response to treatment (Sugrue, 1983). More recent investigations have also shown that administration of DMI to depressed subjects had no effect on levels of homovanillic acid, the principal metabolite of dopamine, in a measure of brain neurotransmitter production. In this investigation, DMI administration did increase norepinephrine production and overall cerebral metabolism (Lambert, 2000). 

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